docs: def juju_version():
      """Full version string (eg. '1.23.3.1-trusty-amd64')"""
      # Per https://bugs.launchpad.net/juju-core/+bug/1455368/comments/1
      jujud = glob.glob('/var/lib/juju/tools/machine-*/jujud')[0]
      return subprocess.check_output([jujud, 'version'],
                                     universal_newlines=True).strip()